基于相位调制的非均匀DFT调制滤波器组的构造算法

Construction of Nonuniform DFT Modulated Filter Banks via Phase Modulation

由于具有灵活的频率划分能力,非均匀滤波器组在语音、图像等信号的处理中有着广泛的应用。该文针对非均匀DFT调制滤波器组无法直接合并构造的缺点,提出一种基于相位调制的构造方法。在该方法中,非均匀DFT调制滤波器组的子带滤波器由均匀DFT调制滤波器组经子带合并和相位调制获得。构造所得的非均匀滤波器组与原均匀滤波器组的重构特性近似相等。同时推导出非均匀子带滤波器具备良好频率特性的条件。理论分析和仿真结果均表明了所提的构造方法的有效性。

Owing to its flexible frequency decomposition ability, nonuniform filter banks are widely applied to speech and image signal processing. However, the nonuniform Discrete Fourier Transform （DFT） modulated filter bank can not be constructed by directly merging certain subbands of the uniform one. In order to overcome this deficiency, a novel construction approach is proposed, in which the subband filters of the nonuniform filter bank are obtained by jointly employing the subband merging and phase modulation of the uniform one. The resultant nonuniform filter bank exhibits the very approximate overall performance as the uniform one. Moreover, the conditions are derived for the nonuniform DFT modulated filter banks to possess satisfactory frequency characteristics. Both the theoretical analysis and simulation results show the effectiveness of the proposed method.